#include "sparklinecontent.hpp"

#include <qmath.h>
#include <qpainter.h>
#include <qpen.h>

namespace ZShell::components {

SparklineContent::SparklineContent(QQuickItem* parent)
	: QQuickPaintedItem(parent) {
	setAntialiasing(true);
}

qreal SparklineContent::stepX() const {
	if (m_historyLength < 2 || m_viewportW <= 0.0) return 0.0;
	if (m_sliding) return m_viewportW / static_cast<qreal>(m_historyLength - 1);

	const int len = qMax(
		2,
		(m_line1 && m_line1->count() >= 2) ? m_line1->count()
										   : (m_line2 ? m_line2->count() : 2));
	return m_viewportW / static_cast<qreal>(len - 1);
}

void SparklineContent::setViewportSize(
	qreal viewportWidth, qreal viewportHeight) {
	if (qFuzzyCompare(m_viewportW, viewportWidth) &&
		qFuzzyCompare(m_viewportH, viewportHeight))
		return;
	m_viewportW = viewportWidth;
	m_viewportH = viewportHeight;
	invalidate();
}

void SparklineContent::setLine1(internal::CircularBuffer* buffer) {
	if (m_line1 == buffer) return;
	if (m_line1) disconnect(m_line1, nullptr, this, nullptr);
	m_line1 = buffer;
	connectBuffer(buffer);
	invalidate();
}

void SparklineContent::setLine2(internal::CircularBuffer* buffer) {
	if (m_line2 == buffer) return;
	if (m_line2) disconnect(m_line2, nullptr, this, nullptr);
	m_line2 = buffer;
	connectBuffer(buffer);
	invalidate();
}

void SparklineContent::connectBuffer(internal::CircularBuffer* buffer) {
	if (!buffer) return;
	connect(
		buffer,
		&internal::CircularBuffer::valuesChanged,
		this,
		&SparklineContent::invalidate);
	connect(buffer, &QObject::destroyed, this, [this, buffer]() {
		if (m_line1 == buffer) m_line1 = nullptr;
		if (m_line2 == buffer) m_line2 = nullptr;
		invalidate();
	});
}

void SparklineContent::setLine1Color(const QColor& color) {
	if (m_line1Color == color) return;
	m_line1Color = color;
	update();
}

void SparklineContent::setLine2Color(const QColor& color) {
	if (m_line2Color == color) return;
	m_line2Color = color;
	update();
}

void SparklineContent::setLine1FillAlpha(qreal alpha) {
	if (qFuzzyCompare(m_line1FillAlpha, alpha)) return;
	m_line1FillAlpha = alpha;
	update();
}

void SparklineContent::setLine2FillAlpha(qreal alpha) {
	if (qFuzzyCompare(m_line2FillAlpha, alpha)) return;
	m_line2FillAlpha = alpha;
	update();
}

void SparklineContent::setMaxValue(qreal value) {
	if (qFuzzyCompare(m_maxValue, value)) return;
	m_maxValue = value;
	invalidate();
}

void SparklineContent::setLineWidth(qreal width) {
	if (qFuzzyCompare(m_lineWidth, width)) return;
	m_lineWidth = width;
	invalidate();
}

void SparklineContent::setCurveSmoothing(bool enabled) {
	if (m_curveSmoothing == enabled) return;
	m_curveSmoothing = enabled;
	invalidate();
}

void SparklineContent::setHistoryLength(int length) {
	if (m_historyLength == length) return;
	m_historyLength = length;
	invalidate();
}

void SparklineContent::setSliding(bool sliding) {
	if (m_sliding == sliding) return;
	m_sliding = sliding;
	invalidate();
}

void SparklineContent::invalidate() {
	m_dirty = true;
	applyGeometry();
	update();
}

void SparklineContent::applyGeometry() {
	const qreal pad = m_sliding ? stepX() : 0.0;
	setSize(QSizeF(m_viewportW + pad, m_viewportH));
}

SparklineContent::LineGeometry SparklineContent::buildGeometry(
	internal::CircularBuffer* buffer) const {
	LineGeometry geom;
	if (!buffer || buffer->count() < 2 || m_maxValue <= 0.0 ||
		m_viewportW <= 0.0)
		return geom;
	if (m_historyLength < 2) return geom;

	const int len = buffer->count();
	const qreal step = stepX();
	if (step <= 0.0) return geom;

	qreal startX = 0.0;
	if (m_sliding)
		startX = m_viewportW - (len - 1) * step + step;
	else
		startX = 0.0;

	const qreal h = m_viewportH;
	const qreal strokePad = qCeil(m_lineWidth / 2);
	const qreal curvePad = 3.0;
	const qreal plotTop = strokePad + curvePad;
	const qreal plotBottom = h - strokePad;
	const qreal fillBottom = h;
	const qreal plotH = qMax<qreal>(1.0, plotBottom - plotTop);

	QVector<QPointF> points;
	points.reserve(len);

	for (int i = 0; i < len; ++i) {
		const qreal value =
			qBound<qreal>(0.0, buffer->smoothedAt(i), m_maxValue);

		const qreal x = startX + i * step;
		const qreal y = plotTop + (1.0 - (value / m_maxValue)) * plotH;
		points.append(QPointF(x, y));
	}

	QPainterPath linePath;
	linePath.moveTo(points[0]);

	if (m_curveSmoothing && points.size() > 2) {
		const qreal tension = 1.0;
		const qreal k = tension / 6.0;
		const int n = static_cast<int>(points.size());

		for (int i = 0; i < n - 1; ++i) {
			const QPointF& p0 = points[qMax(i - 1, 0)];
			const QPointF& p1 = points[i];
			const QPointF& p2 = points[i + 1];
			const QPointF& p3 = points[qMin(i + 2, n - 1)];

			QPointF c1 = p1 + (p2 - p0) * k;
			QPointF c2 = p2 - (p3 - p1) * k;

			const qreal segMinY = qMin(p1.y(), p2.y());
			const qreal segMaxY = qMax(p1.y(), p2.y());
			c1.setY(qBound(segMinY, c1.y(), segMaxY));
			c2.setY(qBound(segMinY, c2.y(), segMaxY));

			linePath.cubicTo(c1, c2, p2);
		}
	} else {
		for (int i = 0; i < points.size() - 1; ++i) {
			const QPointF& p0 = points[i];
			const QPointF& p1 = points[i + 1];
			const qreal ctrlX = (p0.x() + p1.x()) * 0.5;
			linePath.cubicTo(QPointF(ctrlX, p0.y()), QPointF(ctrlX, p1.y()), p1);
		}
	}

	geom.stroke = linePath;

	QPainterPath fillPath = linePath;
	fillPath.lineTo(startX + (len - 1) * step, fillBottom);
	fillPath.lineTo(startX, fillBottom);
	fillPath.closeSubpath();
	geom.fill = fillPath;
	geom.hasData = true;

	return geom;
}

void SparklineContent::rebuildIfNeeded() {
	if (!m_dirty) return;
	m_geom1 = buildGeometry(m_line1);
	m_geom2 = buildGeometry(m_line2);
	m_dirty = false;
}

void SparklineContent::paint(QPainter* painter) {
	rebuildIfNeeded();
	if (!m_geom1.hasData && !m_geom2.hasData) return;

	painter->setRenderHint(QPainter::Antialiasing, true);

	auto drawOne =
		[&](const LineGeometry& geom, const QColor& color, qreal fillAlpha) {
			if (!geom.hasData) return;

			QColor fillColor = color;
			fillColor.setAlphaF(static_cast<float>(fillAlpha));
			painter->setPen(Qt::NoPen);
			painter->setBrush(fillColor);
			painter->drawPath(geom.fill);

			QPen pen(color, m_lineWidth);
			pen.setCapStyle(Qt::RoundCap);
			pen.setJoinStyle(Qt::RoundJoin);
			painter->setPen(pen);
			painter->setBrush(Qt::NoBrush);
			painter->drawPath(geom.stroke);
		};

	drawOne(m_geom1, m_line1Color, m_line1FillAlpha);
	drawOne(m_geom2, m_line2Color, m_line2FillAlpha);
}

} // namespace ZShell::components